In the medical and related diagnostic and testing fields, it is often required to take small samples of blood from a subject for the purpose of testing or analysing the blood. A common way of achieving this is by using a small needle or blade to pierce the skin at a location where blood vessels are close to the surface. The combination of a needle or blade and its carrier is commonly known as a “lancet”.
Lancets are typically one-time use devices, with further use of a contaminated lancet giving rise to a risk of infection. Due to this single use nature, it is desirable that lancets are of low cost to manufacture, whilst at the same time being extremely reliable and easy to use. One such device is described in EP0293092. A significant element of the manufacturing cost of lancets is the need to ensure sterilisation. This is often achieved by a post-manufacture irradiation process, where sealed devices are exposed to a dose of radiation. The dose increases with the mass of the lancet, as does the cost.
Many available lancets are provided with removable caps which help maintain sterility, and protect a user from accidental injury. The cap is removed to expose the lancet and may inadvertently be replaced after use. However, once the cap is replaced, it may not be obvious to a user that the lancet has been used. While it may not be possible to reuse the lancet, removing a cap of a used lancet would be unhygienic and potentially frustrating for the user. An additional risk is that a cap is removed and inadvertently replaced without the device having been used, which could result in the lancet being used after its sterility has been compromised by exposure to the atmosphere.